One of the biggest challenges facing designers of absorbent articles is the need for understanding how absorbent articles function in use. Absorbent articles are commonly worn by people to manage a lack of bowel and bladder control, menstruation, and other discharges emanating from their bodies. Wearers of absorbent articles are engaged in a variety of activities including walking, crawling, sitting, cycling, running, playing team sports, and sleeping in a bed. For absorbent articles designed to be worn in proximity with a person's body, such as diapers and feminine care products, the absorbent articles must function in a complex environment in which the degree of intimacy between the absorbent article and the wearer's body varies in use. Not only does the contact between the absorbent article and the wearer's body vary in use, but the geometry of the wearer's body and the geometry of the absorbent article also vary. Changes in the contact between the absorbent article and the wearer's body and changes in the geometry of the wearer's body and the absorbent article can have significant impacts on the ability of an absorbent article to acquire fluid and how comfortable the absorbent article is to wear.
Absorbent articles are also used for cleaning, acquiring fluid from, and treating surfaces. These types of absorbent articles can be generally referred to as wipes. A wide variety of wipes including feminine wipes, diaper wipes, body wipes, toilet tissue, toilet paper, paper towels, facial tissue, handkerchiefs, surface wipes, countertop wipes, and floor wipes are commercially available. Surfaces such as countertops, floors, and table tops may be substantially rigid. Surfaces such as upholstery and animal bodies may be deformable. Surfaces may be treated by using absorbent articles as a dispensing article from which a cleaning aid or surface treatment is distributed. When an absorbent article is used to clean or treat a surface, the absorbent article is often scrunched up by the user, somewhat flattened out to fit within the palm of the user's hand, or affixed to a device to aid the user with using the wipe. The contact between the absorbent article and the surface can vary depending on how the user uses the absorbent article and how much the surface upon which the absorbent article is being used deforms. The intimacy of contact between the absorbent article and the surface upon which the absorbent article is being used can have significant impacts on the ability of an absorbent article to clean, acquire fluid from, and or treat a surface.
Absorbent articles worn in proximity with a person's body are designed to absorb a variety of fluids including urine, vaginal fluid, and bowel movement material. Fluid transfers from within a wearer's body to being contained in an absorbent article in what is essentially a three step process: (1) fluid emanates from the wearer's body, (2) fluid transfers from a surface of the wearer's body to the surface of the absorbent article, and (3) the absorbent article absorbs the fluid. The ability of an absorbent article to acquire fluid as the fluid is transferred off of the surface of the wearer's body is a key performance measure for absorbent articles. For instance, if a sanitary napkin is poorly designed, vaginal fluid that emanates from a woman's vagina is not acquired by the sanitary napkin and remains on the woman's skin in her pudendal region, which can result in discomfort to the woman. Another consequence of poorly designed sanitary napkins is that vaginal fluid that the sanitary napkin fails to capture can migrate until the fluid comes into contact with the woman's undergarments or outer clothing, which can result in a stain.
The ability of an absorbent article in proximity with a body to acquire fluid could be measured directly. For absorbent articles worn in proximity to a human body, there are many challenges to precisely measuring quantities of fluid emanating from the wearer's body, quantities of fluid in contact with the wearer's body, and quantities of fluid on the surface of and in the absorbent article. The challenges include social and physical discomfort of the person upon whom the measurements are made, non-compliance by the person subjected to the testing, as might occur with testing a diaper worn by an infant, and the complexity of the instruments required to make the measurements. An additional challenge is that instruments for analyzing movement of fluids on surfaces and in absorbent articles are often best suited for making measurements involving simple fluids like clean water, not complex fluids, such as urine, vaginal fluid, or bowel movement material.
Computer modeling can be used to analyze the conformance of garments on a human body. The modeling typically involves creating a three-dimensional representation of a human body and a garment and virtually representing a state of the garment when the garment is worn in proximity to the body. Some modeling software allows for movement of the body and enables analyses of the how the garment interacts dynamically with the body, such that the deformations of the wearer's body and the garment can be determined. Absorbent articles worn close to a person's body can be modeled using the same techniques. Thus, designers are able to predict the shape of absorbent articles worn in proximity with a person's body for a variety of in-use conditions. The same approach can be used to analyze how absorbent articles used for cleaning, acquiring fluid from, and treating surfaces interact with a surface such as a cushion or table.
Computer modeling can also be used to analyze movement of fluids in absorbent articles. The modeling typically involves creating a three-dimensional representation of an absorbent article and virtually representing a state of the absorbent article as the absorbent article acquires fluid from a source or dispenses a fluid. Due to the intense computing efforts required to solve equations that describe movement of fluids in absorbent articles, simplified equations that do not address the underlying physical causes of movement of fluid are sometimes used as a surrogate to more fundamentally based models.
The problem remains with how to couple computer modeling related to the shape of a body and an absorbent article worn in proximity to the body or used on the body with computer modeling of movement of fluid from the body to the surface of the absorbent article or within the absorbent article to determine the absorbent article effectiveness of a virtual absorbent article. To solve this problem, there is a need for the ability to quantify fluid transfer from the surface of a body to the surface of an absorbent article for a variety of in-use conditions. Furthermore, there is a need to be able to quantify how absorbent articles absorb fluid for a variety of in-use conditions to determine the absorbent article effectiveness of a virtual absorbent article. Finally, there is a need for the ability to quantify the fluid balance of absorbent articles worn in proximity with a wearer's body for a variety of in-use conditions, without involving human test subjects or physical measurements so that the absorbent article effectiveness of a virtual absorbent article can be determined.